Luan is a type of hardboard plywood that commonly serves as an underlayment for different types of flooring, including resilient vinyl floors. When installed properly, luan underlayment creates a flat, smooth and durable surface to which flooring materials can be attached. Luan is typically quarter-inch thick and therefore does not provide structural support. Install it over a stable subfloor only.
Acclimate the luan to the area in which it will be installed by allowing it to sit in the room for several days. This will prevent it from distorting after it has been attached to the subfloor.
Remove any loose nails, screws, dirt or debris from the subfloor. Fill any holes or gaps in the subfloor with wood filler. Allow the filler to dry, and sand it smooth with 120-grit sandpaper.
Lay a luan sheet in a corner of the room, with quarter-inch spacers holding it away from both walls. Staple it to the subfloor with staples placed every 6 inches around the outside of the board and every 8 inches across its face.
Lay additional sheets moving out from the corner along a wall with eighth-inch spacers between panels. Place quarter-inch wall spacers so that joints between panels line up with the middle of a spacer.
Continue laying panels until you reach an intrusion into the room. When a full panel will not fit between the previous panel and the intrusion, mark and cut it to fit around the intrusion so that it is flush with the other panels in the row. Remember to account for your spacers when measuring.
Start the second row with a half panel in order to stagger the joints in the luan panels. Take care not to place joints in the luan close to joints in the subfloor. Underlayment panels should lie perpendicular to the subfloor panels. Continue laying rows until you reach the opposite end of the room. Cut the final row to width as necessary before stapling the panels.
Inspect your staples to ensure that they are flush with the surface of the luan. Remove any loose or splintered wood created by stapling. Fill any holes in the luan with wood filler. Allow the filler to cure and sand smooth with 120-grit sandpaper.